HPR - HPR1497: Practical Math - Units - Distances and Area, Part 1

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HPR Episode: Using and Converting Between Units of DistanceIntro: Last time, we talked in general terms about units, numbers andhow they might be useful in practice. In this episode, we address somespecific measurement units that apply to distance and area, and how wemight convert from one system to another to better understand both.Entire point of this episode is this: Carry units in calculations on distances and areas, and you'll have more success in using them in your life. Segment 1: Distance and Area in the English system1. Series will focus on English and Metric systems. a. Basic units of distance: inch, foot, yard, mile b. Basic units of area: square inch, square foot, acre, square mile2. Other units of distance and area do exist a. Barleycorn for shoe sizes (1/3") b. Hand for describing horses (4") c. Rod for surveying (16-1/2 feet) d. Chain, also for surveying (4 linear rods, 66 feet, 22 yards) e. Furlong from horse racing and agriculture (220 yards, 10 chains) f. League (about an hour's walk) usually assumed to be 3 miles - Nautical: technical unit that's exactly 3 knots g. Square yard may be used in quotes for carpet installationsTable of Units: http://www.csgnetwork.com/converttable.htmlBrilliant Insight #1: Units of distance were originally arbitrary. We did not standardize on inches, feet, miles, and so on because these are magical units with special merits. They were convenient at the time and place where they were invented. Standards let us talk to each other about distance without having to be in the same place at the same time. We'd have trouble if builders builders had to ask for boards "as long as my arm", or a plank that's "Yea long". 3. Bizarre properties of some English units explained: a. Rod/Chain: Used in measuring farmland and building plots - Rod is 5-1/2 yards, or 16-1/2 feet. - Chain is 4 linear rods, or the length of a surveyor's chain - Could have been longer or shorter. Standard emerged from usage. b. Furlong: Longest row you can plow without resting the animals - Defined as 10 chains (220 yards) c. Acre: If you are on a quiz show, it's 43,560 square feet. Huh? - Defined as the area of a plot that's 1 chain wide by a furlong - Putting definitions together, we peek ahead to make sense of it. 1 acre = 1 chain x 1 furlong x 10 chains